decision table from which decision rules can be inferred by using rough set analysis. The
rules are logical statements (if...then) which represent the relationship between the
description of objects and their assignment to particular classes (see Pawlak 1991; 1992).
Details on rough set analysis both from a methodological and from an applied perspective can
be found in Degoun et al. 1997, Famili et al. 1997, Fayyad et al. 1996, Pawlak 1991, 1992,
Slowinski 1995, van Delft et al. 2000, van den Bergh et al. 1998 and Ziarco 1998.
3.2. Description of case study and database
In this study, we aim to compare the “green performance ” of European cities in terms of the
priorities in decision-making and planning, and their success level from proper evaluation
perspectives. The sample in our study contains European cities which aim to share their
experience in innovative green space policies and strategies. The data and information used
for comparison and evaluation are based on extensive questionnaires obtained from relevant
departments or experts of municipalities in European cities.
For the application of the rough set analysis seven explanatory variables based on
management and planning of urban green spaces were described to identify the green
performance of cities from proper evaluation perspectives. Table 1 summarizes these
variables. The definition for each variable in Table 1 and their data sources are given below.
Al.Proportion of green spaces per 1000 inhabitant (m2): This data is obtained directly from
the representatives of municipalities by questionnaires.
A2.Importance of green spaces to the city compared to other functions: With this question it
is aimed to highlight the importance and the priority of urban green spaces in the city from
the perspective of planning authorities. The importance of green spaces is defined in five
categories; (1) very important, (2) important, (3) medium, (4) less important, (5) not
important.
A3.Recent changes in the total area of green spaces in the last 10 years: This data is obtained
directly from the representatives of municipalities by questionnaires. The changes are defined
as an increase, a decrease or no change in the total area of green spaces in the last 10 years.